The present invention relates generally to bonding of electronic assemblies, and the like, and more particularly, to reworkable, thermally-conductive adhesives and bonding processes for use in fabricating electronic assemblies.
One prior art bonding method relating to the present invention is to pour or trowel prefilled thermal transfer adhesive (prefilled compounds) into cavities of printed wiring assemblies. The problems with the prior art method are that the friction of the prefilled compound can dislodge circuitry and connections causing open circuits and other electrical and thermal problems. Prefilled compounds have a high loading of inorganic filler, such as alumina particles, for example. Forcing the compound into tight spaces may cause damage to the printed wiring assembly. The need for high thermal conductivity attained by high filler content is directly opposed by the need for low friction (attained by lower filler levels). The applications for which the present assignee is concerned tend to require bonding materials that exhibit a high level of thermal conductivity. This means that the filler loading needs to be as high as it can be. Prefilled adhesives have a lower filler content that makes them flowable and such materials tend to trap voids and air bubbles which lower thermal conductivity of the bonded printed wiring assemblies.
Accordingly, it is an objective of the present invention to provide for reworkable, thermally-conductive adhesives and bonding processes for use in fabricating electronic assemblies. It is a further objective of the present invention to provide for reworkable, thermally-conductive adhesives that have higher thermal conductivity compared with prior art adhesives.